Pre-ban mini-14 magazines

To all that live in a state where the AWB did not go away.
Before you go shelling out $100 for a "pre-ban" factory 30 rounder, check this out.
I could not seem to get a straight answer on how to ID a pre 94 mag. So I sent an email to Ruger CS dept for the straight skinny. Here is my email and their reply.

This e-mail is in response to your question or comment of 08/17/2012
Request No: 150993

Comment / question:

Greetings,
I have a question regarding magazines for my mini-14
As I'm sure you are aware, here in MA any magazines over 10 rounds must be pre-ban (mfg before 9/14/94)
How can I tell when a mag was mfg? The ones between 94 and 04 are marked LEO, so those are obvious, but how can I tell the difference between one made pre 94 and one made post 04?
I just want to make sure that I keep it legal.
Thank You,
XXXX XXXXX

Response:Unfortunately, there is no way to tell.

If you need further information, please visit our website at www.ruger.com or contact us at:

For long time Ruger would sell 20 round magazines to the public but didn't sell 30 round magazines to the public until later. There are likely a lot more 20 round magazines around than 30 round magazines. When Ruger started selling 30 round magazines, a friend bought a Mini-14 and he bought a case or two of magazines every pay check. He bought both 20 round and 30 round magazines. The 20 round magazines were $14 and the 30 round magazines were $18.

Depends on whether or not pre-ban is a "positive defense" or not. Some laws totally ban an item, but state it is a positive defense if they meet certain criteria. Here, MGs are like that. Simple possession is all they have to prove, it's on you to prove they are legal with your tax stamp and form.

The mini-14 is reportedly very finicky about mags. If you go to the mini forum 9 out of 10 report problems with non Ruger mags. Therefore the resale on aftermarket mags is very low.
The 30 round ruger mag goes for $40 new, so $25-$30 for a used one would be about right. The unknown one, maybe $20.